Bicycle frames have a rear fork. The rear fork elements are connected by a cross brace. The cross brace is positioned at a predetermined distance from the ends of the fork since it also serves as an attachment for a rim or caliper brake which must reach around the rear wheel tire to engage the rim of the rear wheel. This cross brace is formed with a central aperture or hole extending lengthwise of the bicycle to permit attachment of the brake.
Two types of rear bicycle luggage carriers are generally used--see the referenced book "Bicycle Technology" ("Fahrradtechnik") by Rauch and Winkler. In one arrangement, longitudinal support bars or rods of the luggage carrier are flattened at their forward ends--in relation to a position of the bicycle, in which the handlebars are at the front portion. The flattened end is formed with holes through which the seat clamping bolt can be passed when the carrier is to be attached to the bicycle. In another construction, the forward end of the luggage carrier is closed off by a transverse or cross piece which, again, is flattened in its central portion and is formed with holes so that the flattened part can bear against the rear fork elements and screws can be passed through the holes to tighten against a counter plate.
Both constructions have a disadvantage, namely that the deformed end portion of the carrier support rods or bars present structural elements which are weak with respect to the remainder and, particularly under vibration, are subject to breakage, especially at the transition point between the flattened parts and the support braces or rods which are usually round.
The first construction, in which the carrier frame is attached to the seat clamping bolt, requires exact matching of the carrier to the bicycle. Since rear luggage carriers frequently are "add on" elements which are to be universally applicable to various types and sizes of bicycles, the construction requires stocking of numerous luggage carriers, and thus is not suitable for after-market use. Additionally, the spacing between the clamping bolt and seat attachment sleeve clamp varies in different bicycle frames; it is, therefore, difficult or frequently impossible to make a single luggage carrier which is suitable for many different types of bicycles.
The arrangement in which a flattened end portion of the bicycle luggage carrier bears against the frame itself has been found to lead to fissures, usually at the transition between the flattened portion and the remainder of the luggage carrier which, frequently, is made of round wire stock, which fissures eventually result in breakage.